[David]

There are 9 tabs (2 front, 3 per side and 1 rear) as seen in Bill's pic that have to be cut. A cutoff wheel make that a 5 minute job.

I don't think it's welded at the opening but it has folded metal around the opening that locates and holds the cassette. This is where a cutoff wheel works really well. I stood over the opening on each side and carefully cut this metal just below the top of the opening. My second picture above shows the cut around the opening. That pic is just after the cassette was removed so no additional grinding has been done yet. If you're not familiar with using a cutoff wheel, do some test cuts to learn how to control the rpm and cutting action.

When you get it loose, it looks like the cross bar on the cassette will not clear the reading light housings but if you push the cassette forward and to one side, it'll clear the housing so you can lower that side. Then push it toward the lowered side and the other side will clear and drop down. I started to cut the end of the cross bar (you can see on the left side of the bar on my top picture) before I realized, I didn't need to cut it.